Bicycles driven in whole or in part by assisted power are known in the art. The assisted power complements the driving force generated by the rider of the bicycle, and may replace it altogether. The assisted power can be provided by an internal-combustion or electric motor integrated with the bicycle.
Regardless of the source of the assisted power, the motor being used must be relatively compact and lightweight so that the bicycle is not too heavy or cumbersome to use. These gains in compactness and weight are generally achieved by using smaller motors. Smaller motors, however, are limited in the power they can provide. Furthermore, conventional transmission systems are limited in the amount of torque they can transmit, and thus could not be used with motors having greater power ratings. Therefore, many motors are often not used to their full capacity.